Gene Therapy
Overview Gene therapy is the process in which corrective, therapeutic DNA is inserted into a cell of choice in order to alter the patient's current (potentially problematic) genotype. This alteration may work to replace or fix the patient's mutated genes, develop a therapeutic protein, or make the affected cells stand out to the immune system so they may be recognized as malignant and be removed from the body. In order for the desired gene to be successfully delivered into the body, a vector must be used. The transformed vector may then be inserted into the patient intravenously, or the vector may be introduced to a cell sample in a laboratory before the treated cells are returned to the patient. Usage Somatic Gene Therapy This version of gene therapy delivers the theraputic gene to the somatic cells of the patient; that is to say, the cells that do not carry reproductive genetic material. Treatment of somatic cells will only affect the individual to which the gene therapy was given; no future generations will inherit the patient's genetic modifications. Germline Gene Therapy This version of gene therapy delivers the theraputic gene to the patient's germ cells (egg cells or sperm cells). Genetic alterations to these cells will affect future generations through inheritance. However, this form of gene therapy is banned in numerous countries due to the lack of knowledge regarding possible risks to future generations as well as ethical reasons. Vectors Viral Viral vectors are modified viruses which have been genetically engineered to be non-virulent. Though the infectious genes of the virus are altered or deleted to prevent patient infection, the viral promoter within the gene is left untouched so the inserted gene may still be translated. Viruses that have been used in gene therapy include: * Retrovirus * Adenovirus * Lentivirus * Herpes Simplex Virus * Vaccinia * Pox Virus * Adeno-associated Virus Non-Viral Non-viral methods are generally less effective in transferring the modified gene to the target cells than viral vectors. However, recent advances in technology have increased this method's efficiency. Non-viral methods include: * Plasmids * Injection of naked DNA * Oglionucleotides * Lipoplexes/Polyplexes * Dendrimers * Electroporation * Sonoporation * Magnofection * Gene Gun * Inorganic Nanoparticles Risks Potential risks in gene therapy include infection caused by the virus, an unwanted immune system reaction, targeting of the wrong cells, accidentally creating a tumor, etc. History History on gene therapy developed for ADA patients provided by the NIH genetics exhibit 1985 '-' 'Gene therapy was first used successfully in 1985 by Drs. W. French Anderson and Michael Blaese of the National Heart, Lung, and Blood Institute and the National Cancer Institute during laboratory trials on human cell samples. These initial trials treated two patients for their ADA deficiency. '''1986 '- Studies were performed to test the efficiency of the transfer of theraputic genes to bone marrow cells in animals. '''1988 - Decision made to use white blood cells instead of bone marrow cells, which increased the number of theraputic genes that were taken up by the sample animal cells. 1989 - Test of safety and effectiveness. 1990 - Infusion of theraputic cells given to ADA patient 1993 - Gene therapy used on newborn babies with ADA Present - Original patients are living normal lives Successful Applications Immune deficiencies Hereditary Blindness Hemophilia Blood disease Fat metabolism disorder Cancer Parkinson's disease References Wiki: Gene Therapy Wiki: Vector NIH Genetics Reference: Gene Therapy Mayo Clinic overview of gene therapy Challenges in gene therapy Approaches to gene therapy Successes in gene therapy NIH gene therapy timeline